Electrode assembly



Feb. 18, 1958 M. E. POSEY ELECTRODE ASSEMBLY Filed Feb. 10, 1954 IN V EN TOR. MIL r0531 E. PQSEY BY ATTORNEY lllrllllha'lll m United States Patent ELECTRODE ASSEMBLY Milton E. Posey, College Park, Ga.

Application February 10, 1954, Serial No. 409,340

Claims. (Ci. 324-65) This invention relates to an electrode assembly, and more particularly to an electrode assembly adapted for use with devices for measuring the resistivity of mixes within concrete mixers and the like.

In co-pending application, Serial No. 324,230, entitled Moisture Control Device for Concrete Mixers, filed December 5, 1952, of which I am a joint inventor, an electronic device is disclosed which measures the resistivitybetween a pair, or plurality, of electrodes which pass through the casing and lining of a concrete mixer. A meter incorporated with the device indicates the resistivity of the mix within the concrete mixer, the dial of the same being calibrated as a function of the resistivity to indicate the amount of moisture or water present in the mix.

I have found that while the device disclosed in the above noted application is very efficient to determine the amount of moisture in the concrete mix, the electrodes constructed as disclosed therein do not function with maximum elfectiveness and are difficult to install since the moisture control device must be calibrated for each separate set of electrodes. Further, when the electrodes or lining of the concrete mixer are replaced, the device must be recalibrated.

In the present day concrete mixers of the class to which this moisture control device is particularly adapted,

the unitary lining has been replaced by a lining formed of a plurality of juxtaposed rectangular plates, slightly curved to conform to the inside periphery of the casing, each being separately bolted thereto.

Briefly, the present invention includes an electrode assembly which may be prefabricated and tested at the factory and shipped to a user as a unitary article of manufacture, the electrode assembly being so arranged that it replaces one liner plate of the concrete mixer de scribed above. The concrete mixer is adapted to receive the electrode assembly by having two, and possibly more, holes provided through the casing and the electrode assembly is held in place against the casing by a plurality of bolts. In my inventions, the electrodes are insulated so that they may project through the holes in the casing without fixedly engaging the same, whereby the outer ends may be connected with cables from the control device without danger of short circuits.

Accordingly, it is an object of the present invention to provide an electrode assembly which may be easily and quickly installed in a concrete mixer with but few alterations to that machine.

Another object of the present invention is to provide an electrode assembly capable of manufacture as a unit whereby the adjustments thereof may be made at the source of manufacture and the same may be shipped as one assembled part.

Another object of my invention is to provide an electrode assembly which is simple and economical to manufacture, durable in structure, efficient in operation and easy to install.

Other and further objects and advantages will become apparent from the-following description when taken in conjunction with the accompanying drawings wherein like characters of reference designate corresponding parts throughout the several views, and wherein:

Fig. l is a perspective view of a concrete mixer having installed thereon an electrode assembly constructed in accordance with my invention in conjunction with a moisture control device.

Fig. 2 is an enlarged front view showing the inner face of an electrode assembly constructed in accordance with my invention, said assembly being installed as a liner plate of the inner lining of the concrete mixer illustrated in Fig. 1, the lining being illustrated in fragmentary form.

Fig. 3 is a rear view showing the outer face of the apparatus shown in Fig. 2.

Fig. 4 is an enlarged cross-sectional view taken along line 44 in Fig. 2.

Fig. 5 is an exploded cross-sectional view of my electrode assembly.

Referring now in detail to the embodiment chosen for purpose of illustration, numeral 10 denotes a platform supporting a concrete mixer of the rotary blade type having cylindrical casing 11 provided with ends 12, 12'. Casing 11 is provided with an inner lining denoted generally by numeral 13, the details of which will be dis cussed hereinafter, while a shaft 14 is supported axially by ends 12, 12' so as to be driven by a motor (not shown) in motor box 15. Helical blades 16, connected to shaft 14, are positioned to sweep adjacent inner lining 13 as shaft 14 is rotated.

An insulating edge 17 is provided along the outer edges of blades 16, which edge adapts the machine for use of my electrode assembly with wet mixes and may be deleted when using the concrete mixer for semi-dry mixes. Along the top of casing 11 is a sprinkler pipe 18 which is supported by ends 12, 12' and through which water may be added to a batch of concrete within the mixer. For supplying water to pipe 18, a control valve 19 is connected to the same through flexible hose 20, water being supplied to valve 19 by water inlet pipe 21.

In Fig. l, numeral 22 denotes a cabinet of a typical moisture control device which is adapted to measure electrical resistance. This device comprises an on-otf switch 23, a pilot light 24, a moisture indicating meter 25, a moisture cut-off regulator 26 and a zero shunt adjustment 27. Wires 28 and 29 extend from panel 22 and are respectively connected to electrodes 30 and 31 of my electrode assembly. In the preferred embodiment of my invention, I have illustrated my electrode assembly being connected to a moisture control device whereby water fed through pipe 18 may be automatically cut off when the resistance of the concrete in the mixer drops to a certain point even though it is obvious that my electrode assembly has other uses. While the details of the construction of the moisture control device are not shown, devices which measure resistance, such as are illustrated in U. S. Patents Nos. 2,548,410 and 2,461,111, may be used in conjunction with my electrode assembly without departing from the scope of my invention.

In Figs. 2, 3 and 4-, my electrode assembly is illustrated as installed in a concrete mixer, this assembly taking the place of one of the juxtaposed liner plates 32 which form inner lining 13. The electrode assembly itself comprises a rectangular base plate 33 the same size and shape as one of the plates 32.. This base plate 33 is approximately 20" long and 12.5" wide, and it is concaved to conform to the curvature of casing 11. When base plate 33 is installed as described above, threaded bolts 34 project through the corners of plate 33 and through casing 11, and are held in place by nuts 35, the heads of bolts 34 3 being recessed in base plate 33 so that blades 16 will not damage them as the same are rotated.

In the present embodiment of my invention, electrodes 30 and 31 are arranged along a horizontal center line of base plate 33 approximately 10 to 14 apart. it is apparent, however, that other distances are operable, and in many installations I have found it desirable to arrange several electrodes in various parts of the concrete mixer. In other installations it may be found desirable to have but one electrode to a base plate or have the electrodes arranged on other than a center line.

Each of the electrodes 30 and 31 is identical, 2. crosssectional view of electrode 30 being shown in Fig. 4 for convenience. In Fig. 4, it is seen that electrode 30 comprises a wide disc-shaped concaved electrode head 36 provided with athreaded stem 37 which projects axially therefrom on one side. The peripheral edge 38 of head 36 tapers toward stem 37 and the same is received within a tapered hole 39 within base plate 33, the periphery of the hole being tapered in complementary manner with communicates with the hole receiving head 36, whereby 'disc 4?. simultaneously abuts an annular shoulder 43 and the rear portion of jacket 49. Collar 41 is also provided with an integrally formed peripheral flange 44, also of insulating fibrous material, which retains disc 42 in place. Stem 37 projects outwardly through collar 41 and is provided with a threaded nut 45 and washer 46 which urge collar 41 against disc 42 and draw head 36 within its recess in base plate 33. When nut 45 is loosened, a Wire 28 may be connected around stem 37 and the nut 45 tightened.

Fig. 5 is an exploded view of my electrode assembly and illustrates the method of assemblying and installing the various parts thereof on base plate 33. It is apparent from Fig. 5 that in the preferred embodiment of my invention, head 36 threadably receives stem 37, and insulating jacket 40 is initially a fiat flexible member provided with an aperture through which stem 37 projects. Upon tightening nut 45 on the end of stem 37, Washer 46 is urged against flange 44 to cause the same to engage disc 42 urging it inwardly until disc 42 acts against annular shoulder 43 while stem 37, which threadably receives head 36, draws the same against jacket 4t) and into the recess in base plate 33.

From the foregoing description, it will be apparent that my electrode assembly may be installed as a replace ment for a liner plate 32 by providing appropriately placed holes in casing 11, through which the stems 37 and collars 41 of electrodes .36 and 31 pro'ect. in event the electrode assembly is no longer needed, a conventional liner plate such as one of plates 32 may replace my electrode assembly, thus covering the holes previously made for electrodes 30 and 31.

It will be obvious to those skilled in the art that many variations and modifications may be made in the single embodiment chosen for purpose of illustration without departing from the scope of my invention as defined by the appended claims.

I claim:

1. An electrode assembly comprising a concaved base plate, an electrode head recessed in one side of said base plate, the surface of said electrode head conforming genorally to the surface of said base plate, insulating material surrounding the opposite face and edge of said electrode head, a stem projecting from said electrode head through said insulatingmaterial, abutment means recessed in the other side of said base plate and abutting said insulating material and said base plate, an insulating collar in the central portion of said abutment means through which said stem projects, and means connected to said stem urging said abutment means against said base plate and toward said head to retain said electrode head snugly seated in said base plate.

2. An electrode assembly comprising a concaved base plate, a disc-shaped electrode head recessed in said base plate, the surface of said electrode head being concaved and conforming to the concaved surface of said base plate, insulating material surrounding the opposite surface and peripheral edge of said electrode head, a stern projecting from said electrode head through said insulat ing material, a disc of larger diameter than said electrode head recessed in the other side of said base plate, a central portion of said disc abutting said insulating material and a peripheral portion of said disc abutting said base plate, an insulating collar in the central portion of said disc through which said stem projects, and means connected to said stem urging said disc against said base plate and toward said head to retain said electrode head snugly seated in said base plate.

3. In a mixer of the class having a stationary casing provided with a sectional lining and rotary stirring blades wherein a moisture control device measures the electrical resistance of the material contained therein, the combination with said moisture control device of an electrode assembly, said electrode assembly being characterized by a concaved base plate fixed to the inside of said casing and forming a part of the lining thereof, a disc-shaped electrode head recessed in said base plate, the surface of said electrode head being concaved and conforming to the concaved surface of said base plate, insulating material surrounding the opposite surface and peripheral edge of said electrode head, a stem projecting from said electrode head through said insulating material, a disc of larger diameter than said electrode head recessed in the other side of said base plate, a portion of said disc abutting said insulating material, an insulating collar in the central portion of said disc through which said stem projects, said collar projecting through a hole in said casing, and means connected to said stem urging said disc against said head.

4. In a mixer of the class having a stationary casing provided with a sectional lining and rotary stirring blades wherein a moisture control device measures the electrical resistance of the material contained therein, the combination with said moisture control device of an electrode assembly, said electrode assembly being characterized by a concaved base plate fixed to the inside of said casing and forming a part of the lining thereof, a pair of disc-shaped electrode heads spaced from each other and recessed in 7 said base plate, the surface of said electrode heads being concaved and conforming to the concaved surface of said base plate and being substantially flush therewith, insulating material respectively surrounding the opposite surfaces and peripheral edges of said electrode heads, stems respectively projecting from said electrode heads through said insulating material, discs of. larger diameter than said electrode heads recessed in the other side of said base plate, a portion of each of said discs respectively abutting said insulating material, insulat 1g collars respectively in the central portion of said discs'through which said stems respectively project, said collars projecting through holes in said casing, and means connected to said stems urging said discs respectively against said base plates and toward said heads.

5. in a concrete mixer of the class having a stationary casing provided with a lining and rotary stirring blades 'wherein a moisture control device measures the electrical resistance of the concrete contained therein, the combination with said moisture control device of an electrode assembly, said electrode assembly being characterized by a concaved base plate fixed to the inside of'said casing 5 and forming a part of the lining thereof, a disc-shaped electrode head recessed in said base plate, the surface of said electrode head being concaved and conforming to the concaved surface of said base plate, insulating material surrounding the opposite surface and peripheral edge of said electrode head, said peripheral edge and the complementary portion of said base plate tapering toward said head, a stem projecting from said electrode head through said insulating material, a disc recessed in the other side of said base plate, a portion of said disc abutting said insulating material and a portion of said disc abutting said base plate, an insulating collar in the central portion or" said disc through which said stem projects, said collar projecting through a hole in said casing, and means connected to said stem urging said disc against said base plate and toward said head.

References Cited in the file of this patent UNITED STATES PATENTS 1,731,597 Spear Oct. 15, 1929 1,797,766 Frye Mar. 24, 1931 1,930,831 Webb Oct. 17, 1933 1,961,965 Fisher June 5, 1934 2,016,920 Fisher et al. Oct. 8, 1935 2,616,949 Cade Nov. 4, 1952 2,650,343 Thompson Aug. 25, 1953 

